1. Field of the Invention
The present invention relates to a tape/ribbon composite cassette freely mountable in a label printer. The tape/ribbon composite cassette includes a tape cassette housing a tape, which serves as a print medium on which characters and the like are printed by the printer, and a ribbon cassette freely detachably mounted in the tape cassette. The present invention relates particularly to improving configuration for facilitating mounting and detaching the ribbon cassette in and out of the tape cassette and to improving positioning of the ribbon cassette in the tape cassette when the ribbon cassette is in a mounted condition in the tape cassette.
2. Description of the Related Art
Japanese Patent Application (KOKAI) No. HEI-2-106555 describes a tape-shaped label printer, which prints characters and marks, such as alphabetic characters and symbols, on a tape printing medium. The label printer is suitable for making labels to adhere to the backs of file folders. A variety of tape cassettes housing a print tape, which serves as a print medium, and an ink ribbon are available to print labels in various colors and with various widths. To change the print color or the width of the label to be produced, the tape cassette in the label printer is changed to one housing a tape with the desired width and an ink ribbon of a desired color.
Japanese Utility Model Application (KOKAI) No. HEI-3-74956 describes a composite cassette used in a label printer for preparing tape-shaped labels. The composite cassette includes an independent tape cassette and a ribbon cassette. The tape cassette houses a tape, which serves as a print medium, and is freely detachably mounted in the printer. The ribbon cassette, which houses an ink ribbon, is freely detachably mounted in the tape cassette. Various ribbon cassettes are available for housing various colored ribbons. This configuration allows allowing printing labels in various colors.
A housing opening is provided in the tape cassette for mounting the ribbon cassette in the tape cassette. The outer periphery of the ribbon cassette and the peripheral wall surface of the housing opening are formed with the same shape for positioning the ribbon cassette in the tape cassette when mounting the ribbon cassette in the tape cassette. The outer peripheral surface of the ribbon cassette is guided and fixedly positioned by the peripheral wall of the housing opening.
The tape cassette and the ribbon cassette are formed with head insertion portions through which a print head of the printer is inserted from underneath when the tape cassette is mounted to the printer. Ink ribbon from the ribbon cassette contacts the print head when transported through the head insertion portion. Tape introduced from the tape cassette contacts the outer surface of the ink ribbon at the print head. In other words, where the tape and ink ribbon are in opposition with the print head, the ink ribbon is sandwiched between the tape and the print head. A platen presses the tape against the ink ribbon and the print head. Ink from the ink ribbon can be selectively transferred to the tape by selectively energizing the print head.
As mentioned above, the ribbon cassette is guided, positioned, and fixed with regards to the tape cassette by the compatible fit of the outer peripheral surface of the ribbon cassette and the peripheral wall of the housing opening. However, in order to be able to mount the ribbon cassette into the housing opening of the tape cassette, a small gap must be provided between the peripheral wall of the housing opening and outer peripheral wall of the ribbon cassette.
If this small gap is too large, the ribbon cassette will be loosely held in the tape cassette so that precision at which the ribbon cassette is positioned in the tape cassette drops. Print quality suffers as a result because when the ribbon cassette is loosely held in the tape cassette, the ribbon is unstably transported between and in the vicinity of the print head and the platen. The position of the ink ribbon to the tape fluctuates so that a set print quality can not be achieved.
On the other hand, if the gap between the peripheral surface of the housing opening and the outer peripheral surface of the ribbon cassette is reduced to a minute gap to form a tight fit between the tape cassette and the ribbon cassette, it becomes difficult to smoothly mount the ribbon cassette to the tape cassette. Also, if the ribbon cassette expands because of heat, the ribbon cassette can become stuck in the tape cassette.